The present invention relates to electronic component packaging, and pertains particularly to a rod-shaped inductor especially adapted for surface mounting.
For many years, electronic circuit boards have been fabricated by interconnecting a plurality of electronic components, both active and passive, on a planar printed circuit board. For many years a conventional PC board has comprised an Epoxy/fiberglass laminate substrate clad with a sheet of copper, which has been etched to delineate the conductive paths. Holes have been drilled through terminal portions of the conductive paths for receiving electronic component leads, which were subsequently soldered thereto. As used herein the term "PC" board shall mean any insulative substrate on which has been formed one or more conductive traces or paths for supporting and interconnecting one or more electronic components.
More recently, so-called surface mount technology has evolved to permit more efficient automatic mass production of circuit boards with higher component densities. With this approach, certain packaged components are automatically placed at preselected locations on top of a PC board, so that their leads are registered with, and lie on top of corresponding solder paths or pads. The PC board is then processed by exposure to infrared or vapor phase soldering techniques to re-flow the solder and thereby establish a permanent electrical connection between the leads and their corresponding conductive paths on the PC board.
The increasing miniaturization of electrical and electronic elements and high density mounting thereof has created increasing problems with electrical isolation and mechanical interconnection. In particular, such miniaturization creates more difficulty establishing reliable and efficient connection between packaged components and egress hardware or terminals. Presently known interconnect methods severely limit the ability to provide density and reliable electrical and mechanical isolation between distinct egress or terminal points due to space limitations.
Among the electronic components that must be surface mounted on PC boards are multi-section bobbins. A bobbin is a small insulated (dielectric) spool which serves as a support for an inductive coil or wire wound resistor. The current technique of surface mounting a bobbin 10 to a PC board 12 is illustrated in FIG. 1. A pair of flying leads 14 and 16 made of wire extend from opposite ends of a coil 18 wrapped around the bobbin 10. It is difficult to control the length and height of these wire leads. The wire is usually very fine gauge, e.g. AWG 24 to AWG 50. The portion of the wires 14 and 16 next to the solder joints 18 and 20 are covered by the wick-up solder. Invariably this results in a brittle weak point. Movement of either the wire or the component can result in a broken wire or a micro-crack, causing a serious reliability problem. Flying leads leads are frequently broken as a result of thermal expansion and contraction of the leads and/or terminals.
The aforementioned U.S. patent application Ser. No. 07/825,986 discloses a surface mounted multi-section bobbin including an elongated support body. This body is constructed of a non-conducting material having a plurality of curved winding support areas bound on each side by a generally rectangular mounting member having recesses in opposed surfaces thereof. The bobbin further includes a combined mounting and lead terminal member having opposed gripping fingers engaging the recesses. One of the fingers has a free end extending outward therefrom for connecting with a lead wire. The base portion of the terminal member overlies a solder pad on the PC board.
It would desirable to provide an improved package and method of mounting of a multi-section bobbin without the necessity of fabricating and attaching a separate lead terminal member.